In the handling of sheet material such as is used for building construction, it has been common in recent times to provide a portable sheet bending brake wherein sheet material is clamped between an anvil member and a clamping surface and a bending member is hinged for bending the sheet material about the anvil member. Typical sheet bending brakes are disclosed in U.S. Pat. Nos. 3,161,223, 3,481,174, 3,482,427, 3,559,444, 3,817,075 and 4,240,279.
As shown, for example, in the aforementioned U.S. Pat. Nos. 3,161,223, 3,559,444, 3,817,075 and 4,240,279, the anvil member is clamped into position by means of a backing plate that has inclined cams underlying a portion of the fixed frame so that when the plate is moved longitudinally by a hand lever, the cams are moved into and out of position clamping and unclamping the backing plate.
In the aforementioned U.S. Pat. Nos. 3,481,174 and 3,482,427, the anvil is supported by pivoted bars that, in turn, are connected by links to a handle that is pivoted on the frame of the brake so that rotation of the handle moves the bars and, in turn, the anvil into and out of clamping position.
It has also heretofore been suggested that eccentric cams be utilized for moving the anvil member into and out of position as shown, for example, in U.S. Pat. Nos. 3,383,899, 4,092,841 and 4,081,986.
Among the objectives of the present invention are to provide a portable sheet bending brake which is lighter in weight; which utilizes eccentric cams wherein the cams are not normally exposed but are accessible for easy adjustment, are easier to assemble and disassemble, and produce a positive and firm clamping of the anvil and, in turn, the sheet; wherein the sheet bending brake incorporates a novel stop for positioning the sheet to be bent; wherein the sheet bending brake incorporates frame members that have a novel construction; wherein the sheet bending brake incorporates novel extruded fixed and bending members; wherein the sheet bending brake involves a novel protective strip for the anvil member about which the sheet is bent.